Phased array antennas include a plurality of antenna elements spaced apart from each other by known distances coupled through a plurality of phase shifter circuits to either or both of a transmitter or receiver. There is a desire to lower acquisition and life cycle costs of radio frequency (RE) systems which utilize phased array antennas (or more simply “phased arrays”). One way to reduce costs when fabricating RF systems is to utilize printed wiring boards (PWBs) (also sometimes referred to as printed circuit boards or PCBs) which allow use of more effective manufacturing techniques.
As is known, phased array antenna systems are adapted to produce a beam of radio frequency energy (RF) and direct such beam along a selected direction by controlling the phase (via the phase shifter circuitry) of the RF energy passing between the transmitter or receiver and the array of antenna elements. In an electronically scanned phased array, the phase of the phase shifter circuits (and thus the beam direction) is selected by sending a control signal or word to each of the phase shifter sections. The control word is typically a digital signal representative of a desired phase shift, as well as a desired attenuation level and other control data.
Phased array antennas are often used in both defense and commercial electronic systems. For example, Active Electronically Scanned Arrays (AESAs) are in demand for a wide range of defense and commercial electronic systems such as radar surveillance, terrestrial and satellite communications, mobile telephony, navigation, identification, and electronic counter measures. Such systems are often used in radar for land base, ship and airborne radar systems and satellite communications systems. Thus, the systems are often deployed on a single structure such as a ship, aircraft, missile system, missile platform, satellite or building where a limited amount of space is available.
AESAs offer numerous performance benefits over passive scanned arrays as well as mechanically steered apertures. However, the costs that can be associated with deploying AESAs can limit their use to specialized military systems. An order of magnitude reduction in array cost could enable widespread AESA insertion into military and commercial systems for radar, communication, and electronic warfare (EW) applications. The performance and reliability benefits of AESA architectures could extend to a variety of platforms, including ships, aircraft, satellites, missiles, and submarines. Reducing fabrication costs and increasing the demand of components can drive down the costs of AESAs.
Many conventional phased array antennas use a so-called “brick” type architecture. In a brick architecture, radio frequency (RF) signals and power signals fed to active components in the phased array are generally distributed in a plane that is perpendicular to a plane coincident with (or defined by) the antenna aperture.
Another architecture for phased array antennas is the so-called “panel” or “tile” architecture. With a tile architecture, the RF circuitry and signals are distributed in a plane that is parallel to a plane defined by the antenna aperture. The tile architecture uses basic building blocks in the form of “tiles” wherein each tile can be formed of a multi-layer printed circuit board structure including antenna elements and its associated RF circuitry encompassed in an assembly, and wherein each antenna tile can operate by itself as a substantially planar phased array or as a sub-array of a much larger array antenna.
With the need to have larger antenna apertures and the desire to reduce cost, it has become common to develop the antenna aperture as an array of active aperture subarrays. These subarrays typically have their own internal RF power dividers, driver amplifiers, time delay units, logic distribution networks, DC power distribution networks, DC/DC converters and accessible ports for RF, logic, DC power and thermal management interfaces. It would desirable if each of the subarrays could be manufactured the same and be used interchangeably in the fabrication of the complete array. But when the aperture is formed from subarrays, it has, heretofore, lacked flexibility because the RF distribution networks required for receive beam formation and exciter output distribution are hardwired into the aperture backplane and position dependent in detail, i.e typical AESA apertures are not configured such that the subarrays are interchangeable.
It would, therefore, be desirable to provide an AESA including a plurality of subarray panels where each one of the subarray panels could be interchangeable and therefore facilitate modular aperture construction techniques and reduce cost.